Field of the Invention
The present invention relates to the conveying of wares. Said present invention relates to a carriage for a conveyor, in particular for a gravity-type conveyor, to a conveyor system, in particular a gravity-type conveyor system, and to a method for operating a conveyor system, in particular a gravity-type conveyor system.
Discussion of Related Art
In the case of producing and post-processing of goods, as well as in the case of picking and packing orders, automated conveying of wares plays an important role. Gravity-type conveyors, in particular gravity-type suspended conveying systems herein are distinguished inter alia in that the former enable conveying of wares to be repositioned from the floor to otherwise non-utilized spaces within our without buildings. Suspended conveyor installations are therefore often fastened overhead on supports which are attached to the ceiling, to walls, or to individual pillars which are fastened to the floor.
Moreover, suspended conveyor-systems are used as a buffer between two or more work processes of dissimilar speeds. On account thereof, networked processes may be decoupled in terms of time and/or space, thus enabling disruptions in processes to be remedied without having to stop the remaining parts of a process chain, for example. Differences in the cycle times in processing may be likewise absorbed in this way.
In many sectors, gravity-type suspended conveyors are particularly suitable for building up buffers. This is based on the better utilization of space, as has already been mentioned, on the one hand. On the other hand, said suspended conveyors are relatively energy-saving, since the latter as opposed, for instance, to actively conveyed suspended conveyor systems do not require any drive means such as drive chains, for example, which are routed along the running rails, and often have only a few short actively conveyed sections. On account thereof, gravity-type suspended conveyors may also be decreased or increased in size in a targeted, relatively simple and cost-effective manner, so as to be adapted to changed production requirements.
It is important for the safe operation of gravity-type suspended conveyors that the transportation units (also referred to as trolleys) used have consistently good running properties. In particular, it has to be ensured that transportation units are not inadvertently slowed down or even stopped on sections of the track where conveying is by gravity, since this would lead to delays or interruptions in conveying. Therefore, carriages having wheels or rollers are most often used as transportation units for gravity-type suspended conveyors, since the former generally have less kinetic resistance than those having so-called runners which in turn have a kinetic resistance that is speed-dependent.
Various types of carriage in which the wheels or rollers are developed with a view to the stresses that arise during conveying are known in the prior art.
A rail-conveyed conveying means including a conveyor truck having at least one first, second, and third castor, along a rail track is described inter alia in the as yet unpublished international patent application PCT/CH2014/000032 of the present applicant, which was filed on Mar. 19, 2014. The rotation planes of the at least first, second, and third castor herein are to be disposed at an angle of more than 0° and less than 180° in relation to one another. In order to avoid a tilting torque in the conveying direction of the conveyor trucks which are moved in a mutually independent manner along a conveying path, an arrangement having two or more first, second, and/or third castors is provided. A conveyor installation having such conveying means is likewise described. A system for buffering goods during production, which is associated with the mentioned international patent application, is shown by the present applicant on the internet (http://www.ferag.com/en/1033/Buffering.htm). This system is suitable for a multiplicity of applications. However, in the case of certain applications it may be necessary for the carriages, the rail type, and the rail profile to be specially adapted to the conveyed goods in order for an optimum result to be obtained.
EP 0 856 480 A1 describes a rail-guided transportation means, in particular for conveying print products, and a transportation installation having transportation means of this type. The transportation means comprises a plurality of wheels which are borne on two sides by a guide rail. Herein, movements that are transverse to the conveying direction are said to be prevented by means of a wheel flange which is attached to the wheels. A transportation means according to the description is to be mounted and guided on the guide rail in a largely clearance-free manner by way of wheels that are disposed in a mutually offset manner or by way of anti-friction means.
U.S. Pat. No. 4,531,460 shows a material transportation system which is also suitable for transporting goods having a great weight in a suspended manner. Supports which comprise at least two mechanically connected support heads are described. Herein, one head may serve as a drive head, and the second head may serve as an idler head. The two support heads each have support wheels which run on horizontal running faces of a support rail. The support heads additionally have comparatively small guide rollers which rotate about vertically disposed axes. The supports herein are constructed from a relatively large number of components. Moreover, said supports are unable to absorb torques that are transverse to the running direction but only such torques about axes that are parallel with the running direction and such torques about axes that are vertically perpendicular to the running direction.
EP 0 291 622 B1 shows a rail for guiding a drive chain in a conveyor belt system for handling individual objects, by way of which the objects are movable on selectable paths. The rail is said to comprise a plurality of prefabricated modules which are releasably interconnected, wherein each module forms a portion having a square cross section. According to the publication it is provided that the modules are composed of straight and curved modules, wherein there is only one type of curved module, the curvature radius of the curved modules being determined by the smallest curve radius of the drive chain being used. A guide matching the respective drive chain is disposed on each module on each of the four sides thereof. In this way, ascending or descending paths and curves may be produced using the one type of curved module in that the latter is rotated and the drive chain is obviously disposed in the respective vertical, downwardly directed guide. As shown, the guides that are not occupied by the drive chain are said to serve for receiving connectors of a plurality of modules, for instance.
It has emerged that in the case of the previous systems in which the carriages have to move section by section in a self-propelling manner driven by gravity, obstructions to the running of the trucks principally arise there where the running path comprises spatial curves. Such obstructions which also depend on the type of the transported goods may significantly compromise the operation of such a conveyor system.